b3burner Posted March 21, 2015 Share Posted March 21, 2015 I notice the standard line in most of the default jets and in many of the AI addon aircraft for making sure that contrails appear at the upper altitudes (in the aircraft.cfg file) is: "Max_Contrail_Temperature = -30". And it's usually located within the bracketed section titled "[General Engine Data]". However, there are some jets that don't have this line. In fact no mention of contrails as a keyword even exists in the aircraft.cfg file. Yet... the aircraft is able to produce contrails just fine! My question is, what "alternate language" as a text line in the aircraft.cfg enables them to do so? I've picked apart an aircraft.cfg file that doesn't have the top line, but can produce contrails, and I have yet to figure it out. It's certainly nothing obvious. I notice the POSKY and TDS planes are especially good at producing contrails w/o the standard line. So are some AIG and AIA AI planes, though others are missing the standard line, and were NOT able to make contrails, so I had to add the standard line myself. Thanks, -- John Link to comment Share on other sites More sharing options...
PhantomTweak Posted March 21, 2015 Share Posted March 21, 2015 From the aircraft SDK for FSX: Ambient temperature, in celsius, in which engine vapor contrails will turn on. The default value is about -39 degrees celsius for turbine engines. For piston engines, the contrail effect is turned off unless a temperature value is set here. Essentially, if no temp is specified, -39c is assumed by the Sim. Hope that answer your question :) Pat☺ [sIGPIC][/sIGPIC] Had a thought...then there was the smell of something burning, and sparks, and then a big fire, and then the lights went out! I guess I better not do that again! Sgt, USMC, 10 years proud service, Inactive reserve now :D Link to comment Share on other sites More sharing options...
bam1220 Posted March 21, 2015 Share Posted March 21, 2015 The OP is asking about FS9 not FSX. Would it be the same for both sims? Link to comment Share on other sites More sharing options...
StringBean Posted March 21, 2015 Share Posted March 21, 2015 The OP is asking about FS9 not FSX. Would it be the same for both sims? Yes. WWOD---What Would Opa Do? Farewell, my freind (sp) Never argue with idiots. They drag you down to their level and beat you with experience Link to comment Share on other sites More sharing options...
pschlute Posted March 21, 2015 Share Posted March 21, 2015 As an aside it is worth remembering that aircraft have many of their settings established within the .air file itself. Often these can be amended/overridden by a line in the aircraft.cfg file, but the absense of a particular line from the .cfg file simply means that the values in the .air file are being used. Link to comment Share on other sites More sharing options...
b3burner Posted March 21, 2015 Author Share Posted March 21, 2015 Ok, through experimentation I discovered I was mistaken in my assumption that the "max_contrail_temperature = " line had to be present to display contrails... as Pat noted. Default aircraft often have the "m_c_t = -30" line written in the aircraft.cfg, and flying at standard atm (sea level = 59°F), I'm used to seeing the contrails start to form at about 23,000' (OAT= -30°C). When I didn't see any contrails on some AI aircraft by the time I (/they) got up to 27,000', I just assumed the effect was missing from the aircraft, and that the reason why was because the "m_c_t = -30" line was missing. When in fact, the ability to form the contrails by default is ALWAYS there (as Pat had said). Just, if there's no "m_c_t" line in the aircraft.cfg, it assumes a contrail temp around -39 to -41°C. At standard atmosphere temp 59F at sea level, the contrails won't start to form until around 31,000'. The effect was always there... I just didn't wait long enough to see them form in this case. -- John Link to comment Share on other sites More sharing options...
b3burner Posted March 21, 2015 Author Share Posted March 21, 2015 As an aside it is worth remembering that aircraft have many of their settings established within the .air file itself. Often these can be amended/overridden by a line in the aircraft.cfg file, but the absense of a particular line from the .cfg file simply means that the values in the .air file are being used. Ah yes! I had always wondered where .air files leave off and aircraft.cfg files kick in; as far as splitting the responsibility in "determining" the features of an aircraft. This helps to make that a little more clear. I guess I had always been under the impression that the .air file system is a little more antiquated (like from the FS98~ FS2002 days), and that the inclusion of commands into the aircraft.cfg file was a shift that started to take place, as FS matured into the 2004 and FSX versions. Though I could be wrong in assuming that to be a hard, fast rule. At any rate, I had already looked for contrail commands in the .air file, and the closest thing I could find was "Line #344" -- Boolean command for "Smoke System Available-- (0=False, 1=True)". But it was already set to "0=False", and it occurred to me that contrails are not smoke in the purist sense. That that was probably referring more to the "key I" feature of creating exhaust smoke (on aircraft so equipped); and that that has nothing to do with moisture condensation. Still your reminder of the fact that checking the .air file is another resource I had forgotten about... and a good wake up call on your part. Thanks. -- John Link to comment Share on other sites More sharing options...
PhantomTweak Posted March 21, 2015 Share Posted March 21, 2015 As an aside it is worth remembering that aircraft have many of their settings established within the .air file itself. Often these can be amended/overridden by a line in the aircraft.cfg file, but the absense of a particular line from the .cfg file simply means that the values in the .air file are being used. To the best of my, readily, admittedly, limited knowledge, there is no section of the .air file that deals with contrails. I am frequently in error, however, and am far, far from an expert in anything at all (except maybe F-4 radars, which is very primitive tech, really). I sincerely hoe someone will correct my error, if any, about this :) And yes, most of the settings from the sdk I mentioned are equally applicable to FS9 or FSX both. I've tried a lot of them in FS9 (it's what I use. My poor, old, machine doesn't do FSX very well, not even SE), and they seem to work just as well in either version. The quote I used came from a page on the Microsoft website, part of the Microsoft Developers Network, labeled ESP 1.0, Sim Object Creation Kit. I am not certain any more if it is permissable to link it or not, so I won't, but I am sure a short look about the net will locate it easily enough, should you desire to delve deeper into this. Just remember what happened when the Dwarves delved too deeply in the Mines of Moria, or Khazad Dum. They unleashed...The BALROG! Hehehehehe Pat☺ [sIGPIC][/sIGPIC] Had a thought...then there was the smell of something burning, and sparks, and then a big fire, and then the lights went out! I guess I better not do that again! Sgt, USMC, 10 years proud service, Inactive reserve now :D Link to comment Share on other sites More sharing options...
pschlute Posted March 21, 2015 Share Posted March 21, 2015 Pat I am sure you are right that contrails are part of the sim rather than aircraft themselves and are not part of the .air file. My addition to this thread, as an aside, was to make sure people are aware that a "missing" line from the .cfg file did not of itself mean that the effect/setting was not being used by the aircraft in qustion. Link to comment Share on other sites More sharing options...
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